problem uploading

Hi,
I have a arduino duemilanove which is working for some time.
This week I got new arduino nano and i have some problems uploading code. I chose the right port and the right board on the software.

any one got an idea?

btw...the red RX led is flashing in the beginning.

[color=#ff0000]avrdude: stk500_getsync(): not in sync: resp=0x00
avrdude: stk500_disable(): protocol error, expect=0x14, resp=0x51[/color]

Thank you.